From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx122.postini.com [74.125.245.122]) by kanga.kvack.org (Postfix) with SMTP id 5AEE26B0062 for ; Sun, 30 Dec 2012 00:55:40 -0500 (EST) Message-ID: <50DFD8F4.7040301@cn.fujitsu.com> Date: Sun, 30 Dec 2012 14:02:28 +0800 From: Wen Congyang MIME-Version: 1.0 Subject: Re: [PATCH v5 14/14] memory-hotplug: free node_data when a node is offlined References: <1356350964-13437-1-git-send-email-tangchen@cn.fujitsu.com> <1356350964-13437-15-git-send-email-tangchen@cn.fujitsu.com> <50DA7533.6060407@jp.fujitsu.com> <50DC3C26.6060308@cn.fujitsu.com> <50DCE7C0.8070407@jp.fujitsu.com> In-Reply-To: <50DCE7C0.8070407@jp.fujitsu.com> Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=ISO-2022-JP Sender: owner-linux-mm@kvack.org List-ID: To: Kamezawa Hiroyuki Cc: Tang Chen , akpm@linux-foundation.org, rientjes@google.com, liuj97@gmail.com, len.brown@intel.com, benh@kernel.crashing.org, paulus@samba.org, cl@linux.com, minchan.kim@gmail.com, kosaki.motohiro@jp.fujitsu.com, isimatu.yasuaki@jp.fujitsu.com, wujianguo@huawei.com, hpa@zytor.com, linfeng@cn.fujitsu.com, laijs@cn.fujitsu.com, mgorman@suse.de, yinghai@kernel.org, x86@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-acpi@vger.kernel.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, linux-ia64@vger.kernel.org, cmetcalf@tilera.com, sparclinux@vger.kernel.org At 12/28/2012 08:28 AM, Kamezawa Hiroyuki Wrote: > (2012/12/27 21:16), Wen Congyang wrote: >> At 12/26/2012 11:55 AM, Kamezawa Hiroyuki Wrote: >>> (2012/12/24 21:09), Tang Chen wrote: >>>> From: Wen Congyang >>>> >>>> We call hotadd_new_pgdat() to allocate memory to store node_data. So we >>>> should free it when removing a node. >>>> >>>> Signed-off-by: Wen Congyang >>> >>> I'm sorry but is it safe to remove pgdat ? All zone cache and zonelists are >>> properly cleared/rebuilded in synchronous way ? and No threads are visinting >>> zone in vmscan.c ? >> >> We have rebuilt zonelists when a zone has no memory after offlining some pages. >> > > How do you guarantee that the address of pgdat/zone is not on stack of any kernel > threads or other kernel objects without reference counting or other syncing method ? No way to guarentee this. But, the kernel should not use the address of pgdat/zone when it is offlined. Hmm, what about this: reuse the memory when the node is onlined again? Thanks Wen Congyang > > > Thanks, > -Kame > > > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org